(a) Field of the Invention
The present invention relates to a variable valve system.
(b) Description of the Related Art
A variable valve lift (VVL) system changes a lift amount of an intake/exhaust valve of an engine according to driving conditions. Intake amount can be maximized at high speed/load and minimized at other times, to improve fuel efficiency and reduce exhaust gas.
A variable valve timing portion is provided at one end of each of the intake camshaft and the exhaust camshaft. Cylinder deactivation portions are provided at some of the cylinders. One hydraulic pressure line is provided for the cylinder deactivation portions and another hydraulic pressure line is provided for the variable valve timing portions.
However, when the cylinder deactivation portion continuously operates in a particular cylinder, an electric spark cannot be formed securely. Also, when the cylinder deactivation portion continuously operates in particular cylinder, the bore of the cylinder can be transformed.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.